The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust a mixture of air and fuel to generate torque. The fuel of the air/fuel mixture may be liquid fuel and/or vapor fuel. A fuel system is used to supply liquid fuel and/or vapor fuel to the engine. Liquid fuel is drawn from a fuel tank. A low pressure fuel pump may draw liquid fuel from the fuel tank. The low pressure fuel pump may provide liquid fuel to a high pressure fuel pump or to a fuel injector. Vapor fuel is drawn from a vapor canister of a purge system.
Generally, liquid fuel is contained within the fuel tank. In some circumstances, the liquid fuel may vaporize and form vapor fuel. The vapor canister stores the vapor fuel. The purge system also includes a purge valve and a vent valve (i.e., a diurnal valve). Operation of the engine causes a vacuum (low pressure relative to barometric pressure) to form within an intake manifold of the engine. Selective actuation of the purge valve and the vent valve allows the vapor fuel to be drawn into the intake manifold, thereby purging the vapor fuel from the vapor canister.